The present invention relates to an intraocular lens or pseudophakos which is intended for placement in either the anterior or posterior chamber of an eye after removal of the natural lens of an eye as the result of a cataract condition or other like conditions which destroy the functioning of the natural lens.
Intraocular lenses have been used increasingly in recent times since the use of intraocular lenses provides the cataract patient with remarkable visual acuity. In general intraocular lenses have produced excellent results. Problems still remain in placement of the pseudophakos without inflicting damage to the eye as well as insuring continual fixation of the intraocular lens during the years following cataract surgery. There are several examples of intraocular lenses which fix to the iris. Most notably are the U.S. Pat. No. 3,906,551 issued to Otter and U.S. Pat. No. 4,085,467 issued to Rainin et al. The original intraocular lens development by Strampelli and Barraquer simply wedged the intraocular lens between opposite sides of the anterior chamber of the eye immediately above the iris. The early models occasionally achieved a success but were not acceptable because of fixation problems resulting from improper sizing of the lens structure, and damage to the eye during and after insertion of the lens, as a result of endothelial touch. The original Barraquer lens has been recently revived and achieved greater success by the addition of springy appendages which alleviates necessity of exactly sizing the lens and insertion of a Barraquer type lens in the posterior chamber of the eye. The modern version of the Barraquer lens is known as the Shearing lens which includes a pair of hook-shaped legs which attach to the lens at points generally opposite one another. Surgeons have found acceptable fixation in the posterior chamber in an annular notch known as the ciliary sulcus.
A Shearing lens has several disadvantages in that it may be used with extra capsular surgery only. The Shearing lens is inserted in the posterior chamber by first inserting one appendage through the pupil to the ciliary sulcus, coiling the second appendage, and releasing the same after the lens portion and the secondary appendage has passed through the pupil to the posterior chamber to also obtain fixation at the ciliary sulcus. It has been found that the free end of the springy appendage of the Shearing lens catches eye structures during insertion and centering which adds greatly to the difficulty of insertion. Further, a dilated pupil, which may occur spontaneously or may be medically induced post-operatively, permits the inner edge of the iris to travel under the lens since a single appendage permits bowing. In addition, problems of centering the intraocular lens beneath the pupil occur since the hook-like appendage often catches on the iris, lens capsule, and other portions of the eye. Moreover, other problems associated with twisting about the single appendage, eg: the optical defect of induced cylinder, also occur.
All in all there is a need for a wedging type lens which may be easily placed in the posterior or anterior chamber of the eye which possesses great stability and minimizes damage to the eye during and after insertion.